1. The USA has millions of miles of roadways without Continuous Shoulder Rumble Strips (CSRS) to warn drivers involuntarily leaving the highway resulting in injury, death and property damage. Conventionally, CSRS are formed in-situ in highway pavement surfaces with alternating grooves and ridges.
2. Throughout the USA, county highways rarely have shoulders and lack CSRS. However, these highways permit speeds in excess of 50 mph. At night, or when visibility is poor, or when the driver is distracted, even in broad daylight, the potential for leaving the pavement or veering into oncoming traffic is high.
3. Single vehicle run-off-the-road (SVROTR) crashes are preventable using continuous rumble strips along highways. However, millions of miles of highways do not have CSRS.
4. Continuous shoulder rumble strips (CSRS) are a countermeasure used by highway agencies to prevent single-vehicle run-off-the-road crashes. CSRS are part of highway shoulder and may run parallel to the direction of traffic for the entire length of the highway. In Illinois, the CSRS are rolled into the hot pavement mix as part of resurfacing and shoulder rehabilitation projects. The standard depth of Illinois' CSRS is 1.9 cm (0.75 in.) with a width of 0.9 m (3 ft.) and a spacing of 20.27 cm (8 in.). The outside boundary of the CSRS is 30.41 cm (12 in.) from the edge line. Another approach is to “mill-in” the CSRS after the shoulder surface has hardened.
5. “Noise and vibration produced by shoulder rumble strips are effective alarms for drivers who are involuntarily leaving the roadway. They are also helpful in areas where motorists battle rain, fog, snow, or dust. Rumble strips also help reduce highway hypnosis—a condition where white lines and yellow stripes on long, monotonous stretches of straight freeway can mesmerize and wreak havoc with a driver's concentration.” Source: Federal Highway Administration (FHWA) website.
6. In the USA, single vehicle run-off-the-road (SVROTR) crashes result in approximately one third of all highway fatalities and one-half million people are injured annually.
7. CSRS alert inattentive drivers. “CSRS are bands of raised material or indentations formed or grooved in the shoulders placed continuously to alert drivers starting to drift off the road. They alert drivers by transmitting sound and vibration through the vehicle.” They may be formed on the highway shoulder for the entire length of the highway outside the white or yellow edge line in highways.
8. Benefits of CSRS: 18.3% reduction in SVROTR in all freeways, and 21% reduction in SVROTR in rural freeways. In 1997 dollars, the average comprehensive cost of a SVROTR crash was $62,200.
9. Currently, shoulder rumble strips are either formed on hardtop shoulders or cut into concrete shoulder surfaces. In 1996, in the US, 12,158 fatal crashes were single-vehicle run-off-the-road.
11. Conventional milled or rolled strips on pavement produced in-situ are placed on highway shoulders about 10″ to 12″ from the white/yellow edge line.
13. Prior art prefabricated, raised rumble strips are made of thermoplastics or asphalt and are placed perpendicular to the flow of traffic across the entire width of the traffic lane. They are bonded to pavement surface by approved adhesives recommended by state or federal transportation agencies. These raised individual strips are placed across the entire width of a lane and/or the width of a shoulder for very SHORT DISTANCES to warn traffic of the imminent need to slow down or stop. These thermoplastic warning strips, of various widths, rise about 12 mm or 13 mm above road surface. These prefabricated, raised rumble strips do not run the length of the highway next to the edge line. For an example, see Florida state highway department web pages. U.S. Pat. No. 4,813,811 (issued Mar. 21, 1989) describes such a prefabricated pavement device. It is a “prefabricated composite pavement devise comprising a pavement mixture layer shaped to predetermined width, thickness and cross-section” that is “arranged perpendicular to the flow of traffic for the entire width of the traffic lane” to warn traffic of an impending need to stop or slow down. Traffic warning strips as shown in U.S. Pat. No. 4,813,811 refer to prefabricated rumble strips placed perpendicularly in the path of the traffic for short distances; it is not a CSRS.
14. U.S. Pat. No. 5,327,850 concerns small, non-metallic, extruded roadway markers that cause noise and rumble when a vehicle travels over them. They are bonded by adhesives to the pavement surface of highways. They help “define traffic lanes, identify obstacles” and serve as a substitute for the commonly used roadway marker formed of ceramic and having a semi-hemispherical or button shape. U.S. Pat. No. 5,327,850 shows that prefabricated rumble strips made of non-metallic plastic materials may be bonded to pavement surfaces by adhesives approved by highway agencies.
15. Existing practices of using milled in-situ or other CSRS described above require a wide highway shoulder to accommodate a separate edge line and a rumble strip.
16. Because millions of miles of highways lack shoulders, and because the cost and time of installing the edge line and milled or other forms of CSRS is prohibitive, today, life- and injury-saving CSRS are not installed in millions of miles of highways. Thousands of drivers are exposed to life-threatening accidents because highways lack CSRS. Further, these accidents are destructive to the vehicles and cause billions of dollars in losses in vehicle and property damage.
17. Current practice of painting edge lines and separately milling or rolling CSRS in-situ is time-consuming and disrupts traffic for long periods of time.